The Laboratories of Cellular Physiology, Immunology, and Signal Transduction maintain a group of shared services, housed in separate rooms and sustained by separate skilled personnel. A proportion of each of these services is required for this program project. 1. Dishwashing and autoclave facility: In addition to these services, Lab Helpers assist in the disposal of biohazard material, i.e., all tissue culture products used for human materials, as well as pickup and delivery of mail and purchases. 2. Electron microscopy: Specimen fixation, embedding, sectioning, examination, and photography are performed by a skilled microscopist. 3. Flow cytometry: This facility, which includes FACScan and FACStar Plus instruments, is headed by an electrical engineer. He maintains all instruments, performs all of the cell sorting, coordinates computer management and data storage, and teaches all users how to employ the FACScan including data analysis. We also maintain a centralized bank of hybridomas to more than 2 dozen leukocyte antigens, for use in sorting and analytical experiments, and a central liquid nitrogen storage system.